Apparatus for making solid diamond drills

ABSTRACT

The disclosure is directed to an apparatus for machining solid diamond drills, whrein such drills are machined without regard to natural cleavage lines. The drills are machined to a desired three-dimensional configuration by providing a yieldable engagement of the diamond with an endless machining member in accordance with the surfaces which are to be machined.

United States Patent [191 Cupler, II 7 m1 3,738fi63 June 12, 1973 [76]Inventor:

[ 1 APPARATUS FOR MAKING SOLID DIAMOND DRILLS John A. Cupler, II, 10Cupler Drive, LaVale, Cumberland, Md. 22 Filed: Feb. 5, 1971 [21] Appl.No.: 113,064

[52] US. Cl. 51/50 R, 5l/219 R [51] Int. Cl B24b 3/24 Field of Search51/48 R, 48 HE, 49,

51/50 R, 95 R, 95 LE, 95 WH, 103 R, 105 R,

[56] References Cited UNITED STATES PATENTS 5/1937 Hutchinson 51/48 R1,110,428 9/1914 Edison 51/283 3,374,587 3/1968 Simpkins... 643,74711/1881 Martin 51/50 R Primary Examiner-Donald G. Kelly Attorney-Colton& Stone [57] ABSTRACT The disclosure is directed to an apparatus formachining solid diamond drills, whrein such drills are machined withoutregard to natural cleavage lines. The drills are machined to a desiredthree-dimensional configuration by providing a yieldable engagement ofthe diamond with an endless machining member in accordance with thesurface which are to be machined.

9 Claims, 29 Drawing Figures PAIENTED Jim! 2 summers FIG. B

FIG. 8

. PATENTEDJUNI ems sum 2 or .9

Pmmmw '3 738.063

SHEEI 5 BF 9 HG. I? Mi 20s PATENIED il zae FIG.2|

PATENTEDJUIII 21913 SHEET 8 0F 9' FIG. 23

FIG. 24

PAIENTED 1 3 I975 SHEET 9 OF 9 FIG. 26

FIG. 29

APPARATUS FOR MAKING SOLID DIAMOND DRILLS This is a division ofApplication Ser. No. 842,488, filed July 17, 1969, now U.S. Pat. No.3,626,644.

The invention is directed to apparatus for making solid diamond drills.A solid diamond drillis herein defined as a single or composite diamondstructure having a solid or substantially solid exterior diamond surfacewhich exterior surface is formed in the same overall configuration assteel or other type conventional drills and includes a shank portionwhich is adapted to be anchored or chucked to a rotary machine toolpart, an intermediate neck portion and a shaped machining or workingportion herein described as a blade portion of conventionalconfiguration.

Inasmuch as the formationof a microdrill from a single diamondrepresents a higher order of technological advancement than does theformation of a composite diamond macro'drilLthe detailed description ofthe apparatus involved in the formation of diamond drills will.

be directed to the machining of microdrills from a single diamondfollowed by a more generalized description relating to macrodrills.

The so-called diamond drilling tools known'to the prior art areconventional type tools that are tipped, encased or impregnated,'inwhole or in part, with diamond chipsor dust whichare adhered to orintegrated with the tool by adhesives or the like. These methods ofutilizing. diamonds in connection with a machining tool are the onlyones which were previously considered to be possible since a diamond maynot be formed or shaped-except by other diamonds or by fracture alongnatural; cleavage lines. Previous attempts to shape very small or microdiamondsby grinding withother diamonds or diamond dusthave beenunsuccessful because such attempts have involved conventional grindingor lappingtechniques wherein a workpiece is conventionallychucked orotherwise rigidly supported relative to a grinder or thelike. A verysmall or'micro diamond is unable to resistthe substantial lateral forcesdeveloped during the abrading operation and, consequently, it cannotbeshaped by conventional machining techniques into complexconfigurations.

The technique of forming solid'diamond drills herein disclosed dependsupon'the ability to position a diamond workpiece in a plurality ofworking positions relative to a working tool or tools'wherein, in atleast one of such working positions, the' workpieceis controllablyyieldably biased into machining engagement with a tool. The purpose ofsuch yieldable engagement is to insure that the forces imparted to thediamond workpiece duringthe myriad of necessary machining operations toimpart a conventional complex drill configuration theretodo not reachsuch proportions as would fracture the diamond.

Inasmuch as economic. considerations dictate that a solid diamond drillmachined from a singlediamond must be quitesmall, such as in the sizerange of those tools normally used for microdrilling.techniques, it isapparent thatthe forces, and particularly the'lateral forces, thatmayberesisted by the diamond'workpiece are quite small as in the rangeof a few grams.The man- .ner in which a diamond. workpiece may thus beyieldably biased into machining engagement with at least one tool whileyet insuring the precision formation of a complex conventionalbladeconfiguration to close predetermined tolerances constitutes oneaspect of the invention.

Another important feature of the invention relates to the arrangement ofparts that insures the workpiece will always return to a pre-establishedposition relative to the machining equipment following displacementthereof against the bias of the yieldable means.

In its simplest form, the technique herein disclosed involves supportingan elongated rough diamond workpiece for rotation about an axis adjacentthe counterrotating surface of a diamond machining tool; resilientlybiasing the workpiece toward the axis of rotation thereof representingits nearest approach to the machining tool; periodically moving the axisof rotation in closer proximity to the machining tool until a desiredconfiguration having a circular cross-section is achieved and thenperforming additional machining operations on the workpiece to furthershape the circular cross-sectional configuration thereof to the desireddrill configuration.

Alternatively, and in accordance with a separate embodiment of theinvention; the workpiece may first be formed with a regular polygonalcross-sectional configuration by temporarily disrupting the rotation ofthe workpiece until a flat is machined and thereafter continuing torotate and hold the workpiece against rotation until a desired number offlats or facets are formed. Once the multi-faceted diamond has been soformed the same maybe used in a gem setting as jewelry or thencontinuously rotated and further machined to produce the circularcross-sectional configuration above referred to as an intermediate stepin the formation of a drill.

The manner in which the foregoing steps are performed and the apparatusfor carrying them out will become more apparent from the ensuingdescription when considered in conjunction with the accompanyingdrawings wherein:

FIGS. 1-14 are diagrammatic representations of successive operationsemployed in the formation of a typical diamond drill in accordance withthe invention;

FIG. 15 is a rear perspective view of the machining equipment employedin the formation of diamond drills;

FIG. 16 is an elevational view, with parts broken away, of the frontside of the equipment shown in FIG. 15;

FIG. 17 is an end elevational view of the equipment as viewed from theleft side of- FIG. 16;

FIG. 18 is a fragmentary top plan detail view of an adjustable eccentricand follower which is shown in elevation in FIG. 16;

FIG. 19 is a detailed elevational view, with parts in section, of thepreliminary work station illustrating the biasing and rotation of theworkpiece in Vee. bearings;

FIG. 20-is a fragmentary elevational view of the preliminary workstation as seen from the left side of FIG. 19;

FIG. 21 is a fragmentary elevational detail view of the stop block andangular positioning assembly forming a part of the preliminary workstation;

FIG. 22 is an enlarged cross-sectional view taken along line 2222 ofFIG. 21;

'- FIG. 23 is a top plan view, with parts broken away,

FIG. 24 is a top plan view of the finishing work station;

FIG. 25 is a view taken partly in elevation and partly in section alongline 25-25 of FIG. 24;

FIG. 26 is a more or less diagrammatic illustration of a modified drivesystem that may be used in the practice of the invention;

FIG. 27 is a cross-sectional view of a multi-faceted diamond workpiecethat may be machined utilizing the modified drive arrangement shown inFIG. 26;

FIG. 28 is a fragmentary showing of the manner in which a compositerough diamond workpiece may be prepared for subsequent machiningoperations to form a composite macrodrill; and

FIG. 29 is a cross-sectional view taken along line 29-29 of FIG. 28. I

The basic steps required to machine a solid diamond blade typemicrodrill are schematically illustrated in FIGS. 1-14. FIGS. 1-12represent the operations performed at a preliminary work station andFIGS. 13 and 14 the operations performed at a finishing work station. Abrief review of these Figures will facilitate an understanding of theensuing detailed description of the actual equipment utilized in thepractice of the invention.

An elongated rough diamond chip 10, which may be of gem quality such asa chip remaining from a conventional diamond cutting and/or cleavageoperation, is illustrated in FIG. 1 as being secured in the counterboredend of mandrel 12 as by a form setting material 14 having a low meltingpoint such as soft solder or an appropriate adhesive. The particulardiamond chip illustrated is generally triangular in cross-section as isusual in the case of chips remaining from comventional diamondfracturing, cleavage or cutting operations. The anchored or chucked end16 of the chip may be approximately 0.050 inch and the exposed end ofthe chip would not normally exceed a length to diameter (L/D) ratio ofabout 7:1.

After chip 10 has been mounted in mandrel 12, the mandrel is positionedin Vee bearings 20, to be subsequently described, which define an axis22 of chip rotation. The Vee bearings, mandrel and chip are thenpositioned as shown in FIG. 1 with axis 22 spaced above the cylindricalsurface 24 of machining disc 26 which has a liquid suspension of diamondduct applied to cylindrical surface 24 thereof in a manner to besubsequently explained. The axis 22 is then lowered by a Z positioningmechanism on which the Vee bearings are supported until the high pointor ridge 28 of chip 10 just engages cylindrical surface 24. Resilientbiasing means schematically illustrated by arrow 30 in FIG. 2 urge themandrel into full bearing engagement with conventional non-captive Veebearings 20 and into axial coincidence with axis 22 defined by the Veebearings. Chip l and disc 26 are counter-rotated as indicated in FIG. 2in a manner which will be subsequently explained. The resilient biasimparted to mandrel 12 insures that chip will rotate about axis 22 butcan yield when a predetermined lateral force is applied thereto as whenthe high point 28 engages the disc during each 360 revolution. The chip,obviously, returns to its axis of rotation under the influence of bias30 as the ridge is passed. As ridge 28 is gradually worn down thelateral forces applied to the chip, which may be on the order of 3grams, will not be sufficient to deflect the chip away from the axis ofrotation defined by the Vee bearings and it is this same degree oflateral thrust that the chip can tolerate without damage.

As the machining operation just described continues and the higher sideof the diamond chip is ground away, axis 22 is periodically loweredtoward surface 24 by a timing mechanism and automatic stepper motoruntil a portion 32 of the exposed end 18 of the chip is perfectlycylindrical as shown in FIG. 3. The diamond chip is then removed fromthe counterbored end of mandrel 12 after heating the same to meltmaterial 14 or dissolving the same if not a thermosetting adhesive.

A second mandrel 34 is prepared with a counterbore containing a coppersleeve 36 whose inner diameter is approximately 0.0002 inch less thenthe cylindrical O.D. of chip end portion 32. Mandrel 34 is then heatedslightly until it and the copper sleeve just start to expand, but notsufficient to anneal the mandrel, and approximately 0.050 inch of thecylindrical chip end is press fitted therein as shown in FIG. 4. Therough end portion 16 of chip 10 is now exposed for machining operations,as in FIG. 5, and it is machined to the same cylindrical dimension asend portion 32 in the manner previously described. This second operationon end portion 16 requires much less time since the axial length of theportion to be machined is much less and the lowering of axis 22 towardsurface 24 may proceed in more rapid stepwise advancement.

At the stage of operation illustrated in FIG. 6, the diamond is nowrecognizable as a tool blank and that end of the diamond anchored orchucked in the counterbore of mandrel 34 will henceforth properly bereferred to as the shank 38. Similarly, as will become more apparent asthe description of FIGS. 7-14 proceeds, that exposed end portion of thediamond which will undergo further machining operations to assume theform of a cutting blade will be known as the body, working or bladeportion 40 and the intermediate portion of the diamond interconnectingthe shank and blade portions will properly be referred to as the neck42.

The formation of shank 38 is now complete and it will remain chucked inmandrel 34 both for the remaining machining operations on the neck andblade portions and during its lifetime as a finished drill.

The next step in the formation of blade portion 40 is to form the backtaper. Mandrel 34 is positioned in the Vee bearings with blade portion40 adjacent cylindrical surface 24 and the Vee bearings are positioned,in a manner to be subsequently described, to tilt the axis of rotation22 upwardly through a desired taper angle a shown in FIG. 7 so that neckportion 42, adjacent the mandrel, lies closer to the plane of surface 24than does blade portion 40 remote from the mandrel. The Vee bearings arethen lowered, maintaining the desired taper angle at, until neck portion42 engages machining surface 24. Counter-rotation of the tool blank anddisc accompanied by the timed stepwise lowering of axis 22 as indicatedin FIG. 7 results in the formation of the back taper shown in FIG. 8having the cross-sectional configuration illustrated at 44. In onespecific embodiment, the reduction in neck diameter, indicated at 46,may be 0.002 inch.

It will, of course, be obvious that the back taper could have beenmachined simultaneously with the cylindrical shaping of the rough endportion 16 thus combining the operations illustrated in FIGS. 5 and 7.

After the back taper has been formed, rotation of the tool workpiece isno longer required in the subsequent machining operations to beperformed. Accordingly, and with reference to FIG. 9, the end ofmandrel-34 remote from the diamond tool blank is locked in acounterbored adapter 48 by set screw 50 which adapter has a locatingguide bore 52 and blade guide 54 which defines certain precisepositioning locations required for subsequent machining operations.Blade guide 54 is flexible and formed with a small projecting rib 55extending from a centrallocation on its rear edge for a purpose whichwill become apparent as the description proceeds. Guide bore 52 andblade guide 54 bear a precise angular relationship to each other for apurpose which will become more apparent in the detailed description ofthe apparatus. At this point in the broad description based on theschematic illustrations of FIGS. -14 let it suffice to say that theblade guide 54 positions the mandrel and tool blank for front tapering(overtapering) operations and the bore guide 52 is used in conjunctionwith the formation of the blade point.

The formation of the front taper is the next step and this operationinvolves the machining of two diametrically opposed flats on the bladeportion. Mandrel 34 is again positioned in the Vee bearings with toolblank axis 56 parallel to and spaced above cylindrical machining surface24 and the resilient bias applied thereto. Mandrel 34 is not rotated atthis point and 1 blade guide 54 is engaged .by corresponding guidestructure to insure the precise positioning of the same. Tool blank axis56 is then tilted downwardly relative to surface 24 as shown in FIG. 10and lowered until the large end of the tool blank, remote from neckportion 42, engages the machining surface. The bearing assembly is thenfed downwardly, as previously described, while surface 24 is rotated.This operation continues until the desired fore taper 58 is formed onone side of the tool blank as illustrated in FIG. 10 and more clearlyshown in the cross-sectional views at 60. Mandrel 34 is then removedfrom the Vee bearings, rotated 180 about its own axis and reinserted inthe Vee bearings with blade guide 54 maintaining such position and thefront tapering operation repeated to form the opposing front taperclearlyshown in FIG. 12 and particularly in the cross-sectional views at60.

This concludes the operations performed at the preliminary work station.The remaining operations involve the machining of the cutting point at afinishing work station.

With mandrel 34 still secured in adapter 48 by set screw 50, theassembly is positioned at a finishing station (see FIG. 13) and securedagainst angular movement, about its own axis, by a pin passing throughguidehole 52 in adapter 48 and corresponding bores at the finishingstation. Guide bore 52- and blade guide 54 bear a small angularrelationship to each other which defines a particular angularrelationship between the point flats 62 to be formed at the finishingstation and the front taper flats 58. The adapter and mandrel 34 canpivot, in a vertical plane, about the axis of a pin inserted throughguide bore 52. The mandrel is yieldably biased against machining surface24, as shown in FIG. 13, and overlies a fixed pin stop 64 which limitsthe downward movement of the diamond tool blank. The yieldable bias isschematically indicated at 66 in FIG.

13. Pin stop 64 serves a purpose analogous to the Vee chining surface 24that may be attained by the tool blank. A hair spring provides theresilient bias to hold the tool blank against surface 24 with a forcesufficiently light that thrust imparted thereto during the machining ofthe points may be tolerated by the diamond. When the mandrel isinitially positioned as shown in FIG. 13, it will not engage stop 64;rather the sole support of the assembly at the end remote from guide pinreceiving bore 52 is the end of the diamond tool blank and machiningsurface 24. The hair spring maintains the desired machining pressurebetween the diamond and the machining disc. When mandrel 34 comes torest on stop 64, the pointing operation for one side is completed. Thepin is then removed from guide hole 52, the adapter 48 rotated 180, thepin reinserted and the operation repeated to conclude the pointingoperation and the formation of a solid diamond drill shown in FIG. 14which may now be used in a conventional Vee drilling machine in thenormal manner.

It is to be understood that it is more desirable during each of themachining steps above described to perform the initial machiningoperation with a coarse diamond dust and then substitute a fine diamonddust for a polishing operation. It is also very desirable that themachining disc undergo a very small reciprocating motion, or flutter,parallel to its axis of rotation concomitantly with the rotationthereof. Such reciprocating motion is indicated by the double-headedarrow in FIG. 2. This precludes the formation of grooves in themachining and the machined surface by the diamond dust carried by themachining disc and in abrading contact with the workpiece.

The following detailed description of the equipment, shown in FIGS.15-25, which is actually used to make solid diamond drills illustratesone manner in which the preceding machining steps may be performed.

The apparatus for making a solid diamond drill is illustrated in itsentirety in FIG. 15 and includes a machining disc 26, a bodilyadjustable preliminary work support station 68 where initial machiningoperations are performed on a diamond workpiece and a finishing worksupport station 78. Disc 26 is secured to shaft 72 which is mounted inbearing supports 74 for simulta-.

neous rotary and reciprocatory motion. Rotation is imparted to disc 26by motor 76 drivingly connected to pulley 78, secured to shaft 72, viaflexible drive belt 88. Disc 26 is simultaneously reciprocated by amotor 82 imparting rotation to an adjustable eccentric 84 via flexibledrive belt 86 and gear box 88. The motion of eccentric 84 is transmittedto shaft 72 via shaft 90 supported for reciprocation in bracket 92 andspring biased toward the eccentric by an adjustable spring housingassembly 94, shown in FIG. 16, urging shafts 72 and 90 in the directionof eccentric 84. A roller bearing 96 and ball bearing 98 engageeccentric 84 and shaft 72, respectively, for transmitting axial thruststherebetween. The output shaft 100 from gear box 88 is loosely receivedwithin an oversize non-circular opening 102 in cam 84 whose true centeris at point I04. Adjustment of the eccentric between positions aligningthe true center I04 and an offset center 106 with the axis of shaft 100provides the previously referred to adjustment of the eccentric. Thedesired adjustment is maintained by a nut 108 threaded on shaft 100.

It will be apparent that energization of motors 76 and 82 results in thesimultaneous rotation and reciprocabearings in that it defines theclosest approach to mation of disc 26. The actual reciprocationundergone by the disc along the axis of shaft 72 is quite small, forexample in the range of 0.015 O.l25 inch, as will be apparent from theensuing description.

Preliminary work support station 68 is mounted for linear threedimensional and angular adjustment relative to disc 26 through theintermediary of adjustable support structure which includes conventionalX, Y, Z slide positioners 110, 112, 114 respectively, through which workstation 68 may be linearly adjusted. Additionally, bracket 116 ismounted for angular adjustment relative to slide 114 about an axis 118(FIG. 19) parallel to the axis of shaft 72. Arm 120 on which the actualwork holding equipment is secured as shown in FIG. 16, is mounted onbracket 116 for angular adjustment about axis 122 which extends at rightangles to the axis of shaft 72. Turnbuckle 124 interconnected betweenbar 126, rigid with bracket 116, and the side of arm 120 remote fromaxis 122 is herein illustrated as the means by which the adjustmentbetween arm 120 and bracket 1 16, about axis 122, is effected. Aplurality of conventional gauges 128 of any desired type are provided toregister minute adjustments of the relatively moveable parts of thepreliminary work station. An indicator arm 130 rigidly secured to arm120 for angular adjustment therewith about axis 122 is provided with anindicating pointer 132 cooperating with angular scale 134 to indicatethe elevational position of arm 120 relative to the horizontal and theremaining components of preliminary work station 68. The actual worksupporting equipment 136 (FIG. 23) includes a generally U-shaped bracket138 incorporating conventional jewel Vees 140, a mandrel pressurebiasing assembly 142, a stop block assembly 144 including stop shaft146, set screw 148 and an indexing pin 150. Stop shaft 146 is providedwith through bores 152 to receive indexing pin 150.

Biasing assembly 142 includes a trunnion 154 mounting a shaft 156 forrocking movement about pivot axis 158. A fork 160 is mounted at one endof shaft 156 and a leaf spring assembly 162 is mounted at the other endof the shaft. Hardened steel rollers 164 are carried at one end of thefork. Trunnion shaft 166 having a keyway coacting with set screw 168 ismounted in sleeve 170. An adjustable pressure adjustment mechanism 172reacting against the undersurface of leaf spring assembly 162 biases thefork mounted rollers downwardly about the fulcrum defined by pivot axis158,

An arm 174 rotatably supports a mandrel drive roller assembly 176 at oneend thereof and is secured, at the other end, to a shaft 178 joumalledin and bridging U- shaped bracket 138. Drive roller assembly 176 isbiased downwardly against the mandrel positioned in the Vee bearings bya flexible drive belt 180 trained underneath two idlers 182, 184 freelymounted on shaft 178 and extending over a drive pulley 186 integral withthe rubber surfaced pressure roller 188 of the drive roller assembly.Belt 180 is driven by motor 190 and tension is applied thereto by anidler 192. When a mandrel 12 or 34 is positioned in the Vee bearings,pressure roller 188 is biased thereagainst and rotated by drive belt180.

Finishing work station 70 is radially aligned with disc 26 and includesa generally U-shaped bracket 194 having a locating pin 196 extendingthrough aligned apertures in the opposite sides of the U-shaped bracket.A spring biasing assembly, consisting of a bent steel wire 198 issupported on a shaft 200 joumalled in a crossbore in the body of theU-shaped member 194 and coacts with a horizontally related stop shaft 64to support the tool and mandrel in position for a finishingoperationsuch as described in connection with the diagrammatic showingof FIG. 13. Support station is provided with X, Y positioning calipers202, 204 for positioning support station 70 relative to the machiningdisc.

It will be apparent that any or all of the slide positioners may bepreprogrammed and/or automatically controlled in any known manner as bythe use of conventional electric stepping motors such as illustrated at206 for automatically controlling the down-feed rate of slide positioner114 and its supported work station 68 through the intermediary of screwshaft 208 in accordance with known parameters. Such parameters mayinclude the most advantageous down-feed rates for each of the operationspreviously described in connection with FIGS. 2, 5, 7 and 10. Diamonddust, in a suitable liquid carrier, is periodically applied tocylindrical surface 24 of disc 26 by an intermittently rotatedapplicator 210. The sequentially 360 counterclockwise rotation of theapplicator brush into fountain 212 and onto disc 26 may be controlled inany desired manner such as by a preprogrammed stepper motor, not shown.Scraper element 214 positioned adjacent disc 26 returns excess liquid tothe fountain and catch basin 216, underlying the disc, conserves thatexcess diamond suspension not removed by the scraper element.

In many instances it may be desirable to rotate the machining disc atupwardly of 2000 RPM which elevated rotational speeds result in anexcessive loss of diamond slurry due to its being thrown off the disc bycentrifugal force. In such instances, it is preferable to extend thecatch basin 216 substantially about the nonworking peripheral portion ofthe disc and apply the slurry immediately in front (considered in thedirection of rotation of the disc) of the work station and place thescraper immediately behind the work station. The slurry may be appliedin such a situation by either dripping it on the disc or through the useof a brush applicator.

The stop block assembly and its mode of cooperation with the mandrels12, 34 and adapter 48 is best illustrated in FIGS. 20-23. For thosemachining operations wherein mandrel 12 or 34 is rotated, such as thosediagrammatically illustrated in FIGS. 2, 5 and 7, the stop blockassembly is positioned as in FIGS. 20 and 23 with the rounded end of themandrel, remote from the diamond, in engagement with a recess 218 formedin one end of stop shaft 146. Stop shaft 146 is provided with a slit 220intersecting recess 218 which receives blade guide 54 of adapter 48 whenmandrel 34 is to be held against rotation. With mandrel 34 held inadapter 48, the stop block assembly is in the position of FIG. 21. Stopshaft 146 is positioned in the two positions indicated in FIGS. 20 and21 by the selective insertion of indexing pin through one of the bores152. One of the primary purposes of the stop block assembly is to insurethe proper positioning of a rotating diamond workpiece relative to themachining disc and, in the case of the non-rotating workpieceoperations, to provide known precise angular relationships for formingthe flats 58.

The manner in which a mandrel may be positioned in and. removed from theVee bearings will now be described in connection with FIGS. 15, 19 and23. In order to remove the mandrel supported diamond workpiece shown inworking position in FIGS. 15, 19, and 23, set screw 222 is backed offand sleeve 224 of pressure adjustment mechanism 172 drops until themanual adjusting disc 226 strikes support 228. This releases the springbias imposed on shaft 156 and fork 160 by leaf spring assembly 162 andallows the same to be pivoted the stop block overlies the lever arm thuspreventing its return to the FIG. 19 position. Clockwise rotation ofpivot arm 174 and the drive roller 176' journalled thereon places belt180 under tension which may be compensated for by the upward yielding ofidler 192 whose supporting arm 234 may be biased downwardly by asuitable spring, not shown. Alternatively, the flexible belt 180 maysimply be manually tensioned to remove the same from idler 192 prior tothe rotation of lever arm 230 in a clockwise direction. Thus with theresilient downward bias imparted to the mandrel by rollers 164 andpressure roller 180 removed, the mandrel supported diamond workpiece maybe removed from the Vee bearings. The insertion of a rotatable mandrelis performed by simply reversing the foregoing procedure.

When it is desired to insert a non-rotatable mandrel, as in theformation of flats 58, the end of mandrel 34 is first secured in adapter48 by set screw 50. The stop block assembly is then backed off to theposition shown in FIG. 21 and the blade guide 54 inserted into slit 220.There is a precise desired angular relationship between the axes ofbores 152, the plane of blade 54 and the axis of bore 52 in the adapter.Inasmuch as blade 54 is formed from a flexible material, such as springsteel, the mandrel and diamond workpiece carried thereby may undergodeflections away from axis 22 in a plane perpendicular to a planeoccupied by blade 54. Protuberance 55 on blade 54 is bottomed in the endof slot 220 and defines a fulcrum about which the blade and itsintegrally related adapter, mandrel and diamond workpiece may undergolimited movement in a plane occupied by blade 54 and which, consideredwith the flexibility of blade 54, accommodates movement of the workpiecein perpendicularly related planes away from axis 22 as lateral forcesare imposed on the workpiece in excess of those known forces which thediamond may successfully resist during the back tapering opera- .tions.

An understanding of the following detailed description of the actualformation of a solid diamond drill will be facilitated by continuedreference to the diagrammatic showings of FIGS. 144 in conjunction withthe description of FIGS. -25.

After the rough diamond chip 111 is secured in the counterbored end ofmandrel 12, as described in connection with FIG. 1, the stop blockassembly is positioned as in FIG. and mandrel 12 is positioned in theVee bearings with the end thereof remote from the work piece abuttingrecess 218. A known downward force is then applied to mandrel 12 throughrollers 164 by adjusting calibrating disc 226 upwardly. Disc 226 may beprovided with appropriate calibration markings corresponding to knownlateral forces that can be tolerated by the particular L/D sizeworkpiece being machined. During the calibrating manipulation of disc226, the additional downward bias applied to the mandrel throughpressure roller 188 and its associated flexible drive belt is taken intoconsideration. A slotted rubber shield 236 is then positioned in groove238 to preclude the possibility of diamond slurry being transmitted fromthe machining disc to the various moving parts of the preliminary workstation.

The X, Y positioners are then manipulated as necessary to position thediamond workpiece in substantial parallel vertical alignment with theaxis of shaft 72 and in overlying relationship to the cylindricalsurface 24 of disc 26. Motor 206 is then energized to drive screw 208 inthe appropriate direction until the high point of workpiece 10 justengages machining surface 24. Motors 76 and 82 are then energized tocause rotation and limited reciprocation of machining disc 26 aspreviously explained. Motor is next energized to impart rotation tomandrel 12 through pressure roller 188. The axis of rotation 22 of thediamond workpiece, when no forces are applied by the machining disc, isobviously that defined by mandrel 12 rotating in the Vee bearingssupport so that axis 22 is a common axis of rotation for both theworkpiece and mandrel.

A very important feature of the invention resides in the fact that thedownward resilient bias imparted to the mandrel through rollers 164 and188 is so selected that upon the application of an upwardly directedforce of known magnitude being imparted to the diamond workpiece byvirtue of the high point of the rough diamond engaging of the machiningdisc; the workpiece may move bodily upwardly away from surface 24. Thelateral forces that may be tolerated by a known L/D diamond workpiece isdetermined empirically and, after taking into consideration the lengthof the lever arm which would be defined between the effective point ofdownward pressure application and the possible points of engagementbetween the workpiece and machining disc; the downward bias impartedthrough rollers 164 and 188 is so selected as to yield before lateralforces sufficient to fracture the diamond are applied thereto. Thus ifthe initial engagement of the high point of the diamond workpiece andthe machining disc were perfectly selected the high point of the diamondwould gradually be worn away due to the counter rotation of these twoelements without the workpiece ever being deflected upwardly away fromthe axis of rotation 22 defined by the Vee bearings. Normally, however,the workpiece will move upwardly as the high point engages surface 24and return to the original axis of rotation as the high point passes themachining surface. Motor 206 is preprogrammed to intermittently move thewhole preliminary work station downwardly after a sufficient period oftime has elapsed to insure that the initial high point has been machinedaway. As intermittent downward movement of the work station continuesover a period of hours the outer end of the workpiece assumes thecylindrical configuration shown in FIG. 2. It must be clearly understoodthat as the axis of rotation 22 is intermittently shifted downwardly, asfrom the position of FIG. 1 to that of FIG. 2, the workpiece is free tomove upwardly away from surface 24 at all times if the lateral forcesimparted thereto exceed the known maximums.

After one end of the diamond is machined to the configuration shown inFIG. 2, mandrel 12 is removed from the Vee bearings, and the workpieceremoved from its counterbored end. The cylindrical end is then pressfitted into its permanent mandrel 34 as indicated and discussed inconnection with the description of FIG. 4. Motor 206 is reversed toraise the preliminary work station, mandrel 34 is positioned in the Veebearings in abutting engagement with'recess 218 and the foregoingprocedure of intermittently lowering the workpiece is repeated, asindicated in FIG. 5, until the overall length of the workpiece iscylindrical as shown in FIG. 6.

The next machining step involves the formation of a back taper ofcircular cross-section. With mandrel 34 remaining in the Vee bearings,motor 206 is energized to raise the work station and turnbuckle 124 isadjusted to pivot the arm 120 and its integrally connected preliminarywork station upwardly relative to surface 24 about axis 122. The degreeof adjustment depends on the back taper desired and is indicated, inFIG. 7, by the angle a. The desired angle a may be directly read fromscale 134 since pointer arm 130 is rigidly carried by arm 120 forangular adjustment therewith about axis 122. Motor 206 is then energizedto bodily lower the work station until an intermediate portion of theworkpiece, which is to be the smallest diameter portion of the neckindicated at 46, just engages the machining disc. The work station issubsequently fed downwardly, as indicated in FIG. 7, until the backtapering operation is completed as indicated in FIG. 8.

The formation of the back taper concludes those machining operationswherein the workpiece is rotated. The remainder of the machiningoperations require precise angular positional relationships between theworkpiece and machining disc while yet retaining the yieldability of theworkpiece and its constant bias toward that axial position of themandrel defined by its rest position in the Vee bearings. For thispurpose, an adapter 48 is provided as best shown in FIGS. 9 and 21.Following the back tapering operation, mandrel 34 is removed from theVee bearings and secured in the counterbored end of adapter 48 by setscrew 50. The stop block assembly is then backed off to the position ofFIG. 21, and mandrel 34 is positioned in the Vee bearings with bladeguide 54 received within slit 220 and projection 55 engaging the rear ofslit 220. Leaf spring 240 reacting against adapter shoulder 242 biasesthe adapter to the left as viewed in FIG. 21. As will be apparent froman inspection of FIG. 21, mandrel 34 is held against rotation but maymove upwardly, under the influence of excessive forces applied to theworkpiece, by pivoting about the fulcrum defined by the engagement ofprojection 55 with the rear flat surface of slit 220. Indexing pin 150insures the fixed angular positioning of stop shaft 146.

Inasmuch as the mandrel is not rotated in the fore tapering operation tobe described; motor 190 is deenergized and pressure roller arm I74 islocked in the raised position by abutment stop 232 and the necessarydownward bias is applied to mandrel 34 by the spring assembly actingthrough rollers 164 alone.

With the parts in the position shown in FIG. 21, work station 68 israised and turnbuckle 124 is adjusted to pivot arm I and the workstation downwardly, as viewed in FIG. 20, about axis 122 to a desireddegree as may be determined from scale 134 for the purpose of machiningthe diametrically opposed fore tapering flats. Motor 206 is thenenergized to lower the work station until the outermost end of theworkpiece just engages surface 24. Subsequent intermittent downwardmovement then continues until the position of FIG. 10 is reachedwhereupon the formation of one of the fore tapering flats is complete.The mandrel and adapter are then removed from the work station, rotatedabout their own axes, and reinserted in the Vee bearings for a furthermachining operation identical with that just described to form thesecond fore tapering flat 58 as indicated in FIG. 11. This completes themachining operations at the preliminary work station and the workpiece,having the configuration shown in FIG. 12, is now transferred along withthe mandrel and adapter to the finishing work station 70.

At the finishing work station, pin 196 is inserted through bore 52 inadapter 48 which, it will be recalled, is angularly offset relative tothe plane of blade 54. Hair spring 198 is then forced downwardly againstmandrel 34 by calibrating manipulation of shaft 200 to resiliently biasthe workpiece against machining surface 24. At this point, mandrel 34 issupported solely by pin 196 at one end and the diamond workpieceengaging disc 26 at the other end. As the disc is rotated in thedirection indicated in FIG. 25, one of the point flats is formed and thepointing of this flat is complete when the mandrel comes to rest againststop bar 64. Pin 196 is then withdrawn, mandrel 34 is rotated 180 aboutits own axis, the pin is reinserted and the pointing operation isrepeated to produce the finished drill shown in FIG. 14.

In most instances, it will be desirable to initially charge fountain 212with relatively coarse diamond dust, such as No. 15 diamond powdersuspended in an organic liquid carrier, and then substitute a finerdiamond dust such as No. 3 powder in connection with each of theseparate machining operations. The fine dust in the micron size range,of course, imparts a high polish to the workpiece. One reason forconcluding each machining operation with a polishing operation is topreclude the formation of a finished matte surface which ischaracteristic of the finish obtained. with coarse powder. Such a mattefinish leaves microscopic hills and valleys on the working edges of thediamond drill. Not only is the sharpness of the drill decreased by sucha matte finish resulting in the necessity for greater infeed pressuresto perform subsequent drilling operations, but the material beingdrilled tends to pack in the microscopic undulations to produce galling.

Although the energization of work station vertical positioning motor 206in connection with the various machining operations has been referred toas an intermittent one, it will be apparent that the downward travel ofthe preliminary work station could be continuous if the geared reductionis sufficiently great to insure a very slow downward travel.

The machining operations herein described may be more specificallydefined depending upon the material from which the disc 26 is made.Thus, if disc 26 is formed from hardened steel, the machining operationsdescribed are essentially lapping operations whereas if disc 26 is asofter metal so that the diamond dust can be embedded therein themachining operations are more akin to grinding.

The drill shown in FIG. 14 may now be positioned in conventional Veemicrodrilling equipment with no modification other than the securementof a drive pulley to mandrel 34 whereby the mandrel becomes the rotatingmachine part in which the drill is chucked. Exemplary of suchmicrodrilling equipment is that manufactured and sold by National JetCompany, Cumberland, Md. under model designation 7M and furtherillustrated and described in National Jet Company Technical BulletinM7-967.

For mass production operations, it is preferred to position a pluralityof preliminary and finishing work stations about the machining disc and,in such case, it is sometimes desirable to modify the equipment wherebythe machining disc is rotated in a horizontal plane to permit greateraccessibility to the various work stations. In such a modification ofthe equipment, the catch basin would be extended about substantially theentire periphery of the machining disc that is not required formachining operations to catch the diamond slurry thrown off bycentrifugal force. Such slurry would then preferably be pumped to anupper level reservoir wherein the slurry suspension is maintained by anysuitable means such as ultrasonic agitation and from whence it would bepermitted to fiow by gravity onto the machining disc at a point just infront of each individual work station for the same general purposedescribed in connection with the high RPM operation of the apparatuspreviously described.

In FIG. 26 is diagramatically illustrated a modified drive system forimportinga positive intermittent rotation to the workpiece whereby thesame may be formed in multi-faceted, rather than circular,cross-sectional configuration. It will be appreciated that the modifieddrive system shown in FIG. 26, wherein primed reference characters referto corresponding parts in the remaining figures, may simply besubstituted for the corresponding elements best shown in FIGS. 19 and23. Timing belt 180' driven by a conventional stepper motor, not shown,imparts positive drive to mandrel 34 through drive roller assembly 176'and a sleeve gear 243 secured to the mandrel. Drive roller assembly 176'includes timing belt drive pulley 186' and integrally related drive gear188'.

Selective energization of the timing belt stepper motor permits anydesired number of flats or facets to be formed on'the diamond workpieceas indicated by the multi-faceted workpiece shown in FIG. 27 since thepositive drive train shown in FIG. 26 allows the mandrel supportedworkpiece to be held against rotation until the stepper motor produces afurther incremental rotation of the same.

A diamond workpiece having the cross-sectional configuration shown inFIG. 27 may then be further shaped for use in a gem setting or it may beconstantly rotated in the manner previously described to produce thedesired circular cross-sectional configuration for forming a diamonddrill.

The advantages to the jewelry industry in being able to produce facetedstones in this manner rather than by the time-consuming and laborioustechniques previously known are obvious.

Once the fundamental machining operations in con nection with theformation of a solid diamond micro drill (i.e. those machined from asingle diamond) are understood, then the application of the sameprinciples to much larger drills made up of a plurality of structurallyintegral diamond chips becomes obvious. Thus, in

FIGS. 28 and 29 is illustrated a solid composite rough diamond workpiece244 comprising a central elongated steel or other rigid support rod 246surrounded by a plurality of rough diamond chips 10'' which diamondchips and support rod are structurally integrated by a suitableadhesive. The support rod 246 could be completely embedded within therough diamond chips 10" and the same handled in the manner previouslydescribed in connection with the formation of the single solid diamonddrill or one end of support rod 246 may extend beyond the surroundingdiamond chips to function as the supporting mandrel. In either event,the integration of a plurality of rough diamond chips in the mannerillustrated in FIGS. 28 and 29 produces a solid composite diamondworkpiece which may be machined in the manner previously described toproduce a solid composite diamond micro drill.

The rigid support rod 246 may, of course, be omitted and the compositediamond workpiece built up solely from adhesively united diamond chipswhich workpiece may then be machined in the manner described inconnection with the single solid diamondworkpiece.

It will be further obvious that the invention could be utilized in themachining of a workpiece wherein diamond chips are embedded throughout asupporting matrix such as compacted metal powders.

I claim:

1. Apparatus for machining solid diamond drills comprising, a machiningelement having an endless machining surface, noncaptive bearing meansfor defining an axis of workpiece rotation, means mounting said bearingmeans and said machining element for relative bodily movement of saidaxis and surface, said mounting means including means positioning themachining surface for machining engagement with the exterior of a soliddiamond workpiece at a location tending continually to displace saidworkpiece from said noncaptive bearing means, means for resilientlybiasing the rotational axis of a solid diamond workpiece toward themachining surface into coincidence with said first named axis, means forimparting counterdirectional movement to said workpiece and saidmachining surface,'and means for selectively controlling said relativebodily movement whereby a solid diamond workpiece may beresilientlybiased toward a desired axis of rotation which undergoes selectiveincrementalmovement relative to said surface for machining saidworkpiece to a a desired external cross-sectional configuration.

2. The apparatus of claim 1 wherein said machining element is a disc andsaid machining surface is a cylindrical surface, and said apparatusfurther includes means for charging said cylindrical surface withdiamond slurry.

3. The appartus of claim 1 including a finishing work station spacedfrom said bearing means and means at said finishing work station fornon-rotatably supporting and yieldably biasing a diamond workpieceagainst said machining surface.

4. Apparatus for machining diamond drills comprising, a rotary machiningdisc having a cylindrical machining surface, a bodily movablepreliminary work station including non-captive Vee bearings defining apositional axis for an elongate workpiece, yieldable means mounted atsaid preliminary work station for biasing said workpiece into said Veebearings and in the direction of said machining surface, drive means forimparting counter rotational movement to a workpiece and said machiningdisc, means for engaging and disengaging the drive means for saidworkpiece, support means mounted at said preliminary work station forsecuring a workpiece against rotation in said bearings, a finishing workstation spaced from said preliminary work station including means forsupporting a workpiece for limited pivotal movement into and out ofengagement with said machining surface, and means at said finishingstation for yieldably biasing a workpiece into engagement with saidmachining surface.

5. The apparatus of claim 1 wherein the mounting means comprises meansfor canting said axis relative to said surface for imparting a taper toa solid diamond workpiece.

6. The apparatus of claim 2 further comprising means for rotating saiddisk about an axis of rotation and means for linearly oscillating saiddisk along said last mentioned axis.

7. Apparatus for machining diamond drills comprising, a bodily moveablework station including noncaptive Vee-bearings defining a positionalaxis for an elongate workpiece, a rotary machining disk having acylindrical machining surface, means mounting said machining disk forengaging the machining surface on the exterior of a solid diamondworkpiece, yieldable means mounted at said work station for biasing saidworkpiece into said Vee-bearings and in the direction of saidcylindrical machining surface, drive means for impartingcounterrotational movement to said workpiece and said machining disk,and means for engaging and disengaging thedrive means.

8. Apparatus for machining diamonds comprising, a machining elementhaving an endless machining surface, noncaptive bearing means definingan axis of workpiece rotation, means mounting said bearing means andsaid machining element for relative bodily movement of said axis andsurface, said mounting means including means positioning said machiningsurface for machining engagement with the exterior of a solid diamondworkpiece at a location tending continually to displace said workpiecefrom said noncaptive bearing means, means for resiliently biasing therotational axis of a solid diamond workpiece toward the machiningsurface into coincidence with said first named axis, means for impartingrelative movement between said workpiece and said machining surface formachining said workpiece, and means for selectively adjusting theposition of said bearing means and said machining element.

9. The apparatus of claim 8 wherein said last mentioned means includesmeans for canting said first named axis relative to said machiningsurface.

1. Apparatus for machining solid diamond drills comprising, a machiningelement having an endless machining surface, noncaptive bearing meansfor defining an axis of workpiece rotation, means mounting said bearingmeans and said machining element for relative bodily movement of saidaxis and surface, said mounting means including means positioning themachining surface for machining engagement with the exterior of a soliddiamond workpiece at a location tending continually to displace saidworkpiece from said noncaptive bearing means, means for resilientlybiasing the rotatIonal axis of a solid diamond workpiece toward themachining surface into coincidence with said first named axis, means forimparting counterdirectional movement to said workpiece and saidmachining surface, and means for selectively controlling said relativebodily movement whereby a solid diamond workpiece may be resilientlybiased toward a desired axis of rotation which undergoes selectiveincremental movement relative to said surface for machining saidworkpiece to a desired external cross-sectional configuration.
 2. Theapparatus of claim 1 wherein said machining element is a disc and saidmachining surface is a cylindrical surface, and said apparatus furtherincludes means for charging said cylindrical surface with diamondslurry.
 3. The appartus of claim 1 including a finishing work stationspaced from said bearing means and means at said finishing work stationfor non-rotatably supporting and yieldably biasing a diamond workpieceagainst said machining surface.
 4. Apparatus for machining diamonddrills comprising, a rotary machining disc having a cylindricalmachining surface, a bodily movable preliminary work station includingnon-captive Vee bearings defining a positional axis for an elongateworkpiece, yieldable means mounted at said preliminary work station forbiasing said workpiece into said Vee bearings and in the direction ofsaid machining surface, drive means for imparting counter rotationalmovement to a workpiece and said machining disc, means for engaging anddisengaging the drive means for said workpiece, support means mounted atsaid preliminary work station for securing a workpiece against rotationin said bearings, a finishing work station spaced from said preliminarywork station including means for supporting a workpiece for limitedpivotal movement into and out of engagement with said machining surface,and means at said finishing station for yieldably biasing a workpieceinto engagement with said machining surface.
 5. The apparatus of claim 1wherein the mounting means comprises means for canting said axisrelative to said surface for imparting a taper to a solid diamondworkpiece.
 6. The apparatus of claim 2 further comprising means forrotating said disk about an axis of rotation and means for linearlyoscillating said disk along said last mentioned axis.
 7. Apparatus formachining diamond drills comprising, a bodily moveable work stationincluding non-captive Vee-bearings defining a positional axis for anelongate workpiece, a rotary machining disk having a cylindricalmachining surface, means mounting said machining disk for engaging themachining surface on the exterior of a solid diamond workpiece,yieldable means mounted at said work station for biasing said workpieceinto said Vee-bearings and in the direction of said cylindricalmachining surface, drive means for imparting counterrotational movementto said workpiece and said machining disk, and means for engaging anddisengaging the drive means.
 8. Apparatus for machining diamondscomprising, a machining element having an endless machining surface,noncaptive bearing means defining an axis of workpiece rotation, meansmounting said bearing means and said machining element for relativebodily movement of said axis and surface, said mounting means includingmeans positioning said machining surface for machining engagement withthe exterior of a solid diamond workpiece at a location tendingcontinually to displace said workpiece from said noncaptive bearingmeans, means for resiliently biasing the rotational axis of a soliddiamond workpiece toward the machining surface into coincidence withsaid first named axis, means for imparting relative movement betweensaid workpiece and said machining surface for machining said workpiece,and means for selectively adjusting the position of said bearing meansand said machining element.
 9. The apparatus of claim 8 wherein saidlast mentioned means includes means for canting said first named axisrelative to said machining suRface.